1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming system suitable for high-speed print processing.
2. Description of the Related Art
Various printing systems have been proposed in which an information processing apparatus and a printing apparatus are connected via parallel communication means, such as a Centronics interface, or network communication means. In such printing systems, the information processing apparatus (e.g., a host computer) uses a printer driver to convert rendering data (print instruction) sent by an application via an operating system (OS) into print data that the printing apparatus can interpret. The converted print data is sent to the printing apparatus.
The printing apparatus interprets the received print data and performs rendering (rasterization) to generate an image. The generated image is output using a printer engine. The print data contains a set of several kinds of objects (e.g., image, text, and graphic).
As an effective method for reducing time necessary for the image generation in printing in such a printing system, there is a method to perform a plurality of rendering processing in parallel. For example, Japanese Patent Application Laid-Open No. 10-58770 discusses an electronic printing apparatus that divides input print data into a plurality of bands and performs rendering processing for the individual bands in parallel using a plurality of processors. Further, Japanese Patent Application Laid-Open No. 2006-331191 discusses an image forming apparatus and a rendering processing method. In the image forming apparatus and the rendering processing method, overlapped objects are grouped, and rendering processing of the individual groups is assigned to processors and processed in parallel.
However, in the technique discussed in Japanese Patent Application Laid-Open No. 10-58770, depending on complexity (imbalance in the number of contained rendering objects) of the data in each band, the time necessary for the rendering processing in each area may vary. As the result, the parallelism in the processing may vary.
Further, due to the rendering processing time in a band having high complexity, overall processing time may be affected. Further, since the objects are divided into the band units, the relationship among the individual objects may be lost. As the result, the data may not be restored.
In the technique discussed in Japanese Patent Application Laid-Open No. 2006-331191, when overlapping of the objects is determined and the assignment of the processing is performed, the determination and the assignment may be affected by a large-sized object. As a result, the processing may not be evenly assigned.
For example, like a presentation document using a template, when objects such as characters are disposed on a background of an object such as an image or a graphic that extends all over a drawing area, the above-described problems may occur. Further, for the determination of the overlap, it is necessary to spool data of at least one page. Accordingly, start of the processing may be delayed.